[NSRCA-discussion] 747 Snap Entry?

Tue Jul 1 19:46:45 AKDT 2008

My radio says that to me once in  a while.. 

Chris          

--- On Tue, 7/1/08, Matthew Frederick <mjfrederick at cox.net> wrote:
From: Matthew Frederick <mjfrederick at cox.net>
Subject: Re: [NSRCA-discussion] 747 Snap Entry?
To: "General pattern discussion" <nsrca-discussion at lists.nsrca.org>
Date: Tuesday, July 1, 2008, 7:25 PM

I love the "only once" part of that. It brings up 
memories of an old Chuck Yeager flight sim on computer... when you did anything 
crazy you just got a little message at the bottom of the screen that said "Wings 
sheared off"

Matt

  ----- Original Message ----- 
  From: 
  Keith Hoard 

  To: General pattern discussion 

  Sent: Tuesday, July 01, 2008 5:42 
PM
  Subject: Re: [NSRCA-discussion] 747 Snap 
  Entry?

During initial training I was told stories about pilots that 
  would extend the flaps to 2 degrees at altitude to increase fuel efficiency, 
  but to do that you have to pull a couple circuit breakers to disable the 
  leading edge devices (LED's) which are limited by Boeing from being extended 
  above 20,000 feet.  When you do this stunt, you are risking air pressure 
  getting up under the spoilers and causing them to float - thus negating what 
  you're trying to accomplish.  Also, the elevator trim is controlled by 
  the autopilot at altitude . . . if you try to trim the nose up the autopilot 
  will kick itself off.  I could see where an unbriefed pilot resetting the 
  LED circuit breakers at altitude could cause really hideous problems. . . but 
  I highly doubt the Split-S (with 2 of 4??) maneuver . . . more likely a 7.5 on 
  their Straight Flight Out followed by a Zero'd flight due to the LED's 
  departing the aircraft.

Besides, the flaps and trim have no effect on 
  the CG of the airplane. . . it is a function of how the plane is loaded and 
  the current fuel load - which by the way moves the CG forward during flight 
  unless your S/O does something really, really wrong on the fuel 
  panel.   My company is currently trying to load the airplanes with 
  an aft CG for fuel efficiency.

Now, back to the original subject. . . 
  will a swept wing commercial transport aircraft perform a proper snap roll? . 
  . . . My vote is "only once". . .

  On Tue, Jul 1, 2008 at 6:03 PM, Gerald Gallagher <ggall at bellsouth.net> wrote:

  I 
    was a pilot with TWA & knew the captain that is accused of this, also 
    a
TWA Pilot. To this day he denies this ever happened & so do the 2 
    other crew
members that were flying that 727. The loss of altitude was, 
    according to
the three crewmembers aboard was clear air turbulence. I 
    believe the pilot,
but I am prejudice.

Jerry 
    Gallagher

-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] 
    On Behalf Of
rcmaster199 at aol.com
Sent: Tuesday, 
    July 01, 2008 5:47 PM
To: nsrca-discussion at lists.nsrca.org
Subject: 
    Re: [NSRCA-discussion] 747 Snap Entry?

A few of us were 
    discussing just such an occurence recently which
apparently happened by 
    accident and darned near crashed the plane. Dean
remembered the details 
    which went something like this:

The pilot of the 727 about 20 years 
    ago had the plane trimmed as far
aft as possible and had inputed a bit of 
    flap to use fuel most
efficiently. The co-pilot, soon after returning 
    from a visit to the
loo, saw the trimmed flap and flipped the switch to 
    return the flap to
neutral. This action immediately made the plane too 
    tail heavy which
made the plane do a pretty violent half snap to 
    inverted. The pilot
lost close to 25k feet pulling the plane out of the 
    dive, which he did
successfully but not before deploying the gear to slow 
    the crate down.
That had to be some kind of experience

Legend has 
    it that the pilot then went straight to loo himself to
change his 
    britches (G)

Matt

-----Original Message-----
From: Koenig, 
    Tom <Tom.Koenig at actewagl.com.au>
To: 
    General pattern discussion <nsrca-discussion at lists.nsrca.org>
Sent: 
    Mon, 30 Jun 2008 10:25 pm
Subject: Re: [NSRCA-discussion] 747 Snap 
    Entry?

 Hey John,

Out of interest.....has anyone ever 
    attempted a snap in an airliner???

I have heard of a captain doing a 
    slow roll in a 747....but a snap? Is it
possible?? What does a simulator 
    do when pushed to such limits ( I know a
simulator cant snap BTW...well, 
    I assume any way LOL!!)

Tom

-----Original 
    Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] 
    On Behalf Of John Gayer
Sent: Tuesday, 1 July 2008 11:42 AM
To: 
    General pattern discussion
Subject: Re: [NSRCA-discussion] Snap 
    Entry

Actually a snap can occur without any aileron input...but I 
    challenge anyone
to show a pattern ship doing a snap roll on a 45 degree 
    downline without
ailerons.

The approach snap can occur with only 
    the use of elevator and it involves
one wing panel stalling before the 
    other. Try an approach with crossed
controls(aileron/rudder with some 
    power. pull the nose up gradually and see
which wing drops. It will be 
    the wing with the aileron trailing edge down.
This is contrary to what we 
    see in a pattern snap roll which always snaps in
the direction of the 
    aileron deflection thus indicating the lack of any
stalled 
    condition

John

seefo at san.rr.com wrote:

>Just 
    to stir the pot a little further..
>
>I'm not sure a 
    contemporary pattern plane can generate enough pitch
rate to reach 
    critical angle of attack and properly perform a snap roll. I
think it's 
    far more likely that we're seeing nothing but a heavily yawed
aileron 
    roll, with the pitch break only being shown to judges to convince
them 
    there is actually a stall happening, when in fact there is 
    not.
>
>If a snap cannot occur using ONLY elevator and rudder, 
    then the wing is
not stalling. Aileron inputs into a snap actually 
    inhibit flow separation,
as the inboard wing angle of attack is 
    drastically reduced, and the outboard
wing AoA is drastically 
    increased.
>
>But since there is no way to actually determine 
    what is happening
aerodynamically on an F3A airplane, the best a pilot 
    can do is fly the
airplane to what the judges expect to see based upon 
    the rules. It really
doesn't matter what the control inputs are if the 
    airplane LOOKS like it's
doing the right 
    maneuver.
>_______________________________________________
>NSRCA-discussion 
    mailing list
>NSRCA-discussion at lists.nsrca.org
>http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>
>
>
_______________________________________________
NSRCA-discussion 
    mailing list
NSRCA-discussion at lists.nsrca.org
http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
_______________________________________________
NSRCA-discussion 
    mailing list
NSRCA-discussion at lists.nsrca.org
http://lists.nsrca.org/mailman/listinfo/nsrca-discussion

_______________________________________________
NSRCA-discussion 
    mailing list
NSRCA-discussion at lists.nsrca.org
http://lists.nsrca.org/mailman/listinfo/nsrca-discussion

_______________________________________________
NSRCA-discussion 
    mailing list
NSRCA-discussion at lists.nsrca.org
http://lists.nsrca.org/mailman/listinfo/nsrca-discussion

-- 

Keith Hoard
Collierville, TN
khoard at gmail.com

  _______________________________________________
NSRCA-discussion 
  mailing 
  list
NSRCA-discussion at lists.nsrca.org
http://lists.nsrca.org/mailman/listinfo/nsrca-discussion_______________________________________________
NSRCA-discussion mailing list
NSRCA-discussion at lists.nsrca.org
http://lists.nsrca.org/mailman/listinfo/nsrca-discussion

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.nsrca.org/pipermail/nsrca-discussion/attachments/20080702/811bd93c/attachment.html>